Cryptographic method for secure communications

Abstract

Embodiments herein include, for example, a method that includes signing onto an secure communications system; sending a communication message; and transmitting every messages to all devices in a device group, before displaying any message sent or received.

What is claimed is: 
     
       1. A method, comprising:
 signing onto a secure communications system by a client computing device, comprising:
 downloading a symmetrically encrypted data block from a server, wherein the encrypted data block comprises a server-stored secondary password and a server-stored shared-symmetric key; 
 decrypting the encrypted data block with a locally-stored shared-symmetric key; 
 signing onto at least one of a server or service using the server-stored secondary password by the client computing device; 
 generating a secondary password, wherein the generated secondary password is different than the server-stored secondary password; and 
 overwriting the server-stored secondary password with the generated secondary password after the client computing device has downloaded the symmetrically encrypted block comprising a server-stored secondary password and a server-stored shared-symmetric key from the server; 
 
 sending a communication message, comprising:
 encrypting a message with the server-stored shared-symmetric key; and 
 decrypting a received message with the server-stored shared-symmetric key; and 
 
 transmitting every message to all devices in a device group, before displaying any message sent or received, comprising:
 encrypting each message using a locally stored device group shared symmetric key known by all devices in the device group as an encrypted group message and transmitting the encrypted group message to all the devices in the device group, 
 
 wherein upon receiving the encrypted group message, each device of the device group decrypts the encrypted group message with the locally stored device group shared symmetric key and displays the encrypted group message, 
 encrypting the first encrypted message using a locally stored second device group shared symmetric key known by all devices in the second device group as a second encrypted group message and transmitting the second encrypted group message to all the devices in the second device group, 
 wherein upon receiving the second encrypted group message, each device of the second device group decrypts the second encrypted group message with the locally stored second device group shared symmetric key and displays the second encrypted group message.